We propose to develop an entirely new broadband light source optimized for high-resolution optical coherence tomography (OCT). We propose to develop and refine techniques for manipulating the superluminescence properties of diode-pumped Ytterbuim-doped fiber in such a way as to decouple the output power and bandwidth. The goal is to develop a source offering >50mW of output with a bandwidth of at least 100nm and a nearly Gaussian spectral profile. The proposed technology development is intended to enable compact, efficient, cost effective sources appropriate for high-resolution clinical OCT. Clinical systems currently offered have imaging resolution of 10-20 mu/m, limited largely by the performance limitations of practical sources. This target specs proposed here will enable OCT resolution better than 5fm. This performance is particularly compelling for endoscopic minimally invasive biopsy where improved resolution can enhance the detection of cellular abnormalities. The technology may ultimately enable diagnostic quality, real-time optical biopsy.